The present invention pertains to an IP telephony system displaying the locations of telephone terminals.
Since conventional telephony systems are connection schemes based on independent telephone lines, it has not been possible to readily move and modify a telephone terminal or a telephone number. However, in IP telephony systems, whose spread has been observed in recent years, a point has been reached, since they are connection schemes passing through an IP network, where IP telephone terminals can function as telephones anywhere if they are connected to an IP network. In this way, it has become possible, in an IP telephony system, to freely move an IP telephone terminal without any restrictions in particular on the location of connection of the IP telephone terminal.
A general IP telephony system is composed of an IP telephony server, each of the IP telephone terminals, and a network connecting these. The IP telephony server is composed of a telephone terminal management table administering telephone numbers corresponding to the IP addresses of telephone terminals under control; a terminal registration part registering, in the telephone terminal management table, the telephone numbers corresponding to the IP addresses of the telephone terminals under control; and a call connection part connecting, with respect to an outgoing telephone call request from a terminal, the telephone terminal of the other party. Each IP telephone terminal also has a call connection part. In an IP telephony system, it comes about that, by registering the telephone terminal information of each IP telephone terminal as the initial setting in the telephone terminal management table, each of the IP telephone terminals can for the first time carry out outgoing and incoming telephone calls.
As a call connection specification that is utilized in as standardized way in IP telephony systems, there is the Session Initiation Protocol (below abbreviated as SIP). In SIP, basic sequences of a terminal registration method and a call connection method are standardized. In an IP telephony system, taking the opportunity of the time of connection with the network and the time at which power is turned on, the IP telephone terminal sends a REGISTER command, which is a terminal registration request command including the telephone number and the IP address of the IP telephone terminal, to the IP telephony server. The IP telephony server having received this registers IP telephone terminal attribute information, such as the extension number and the IP address of the IP telephone terminal, in the telephone terminal management table by means of the terminal registration part. The IP telephony server returns “200 OK” as the processing result if what is concerned is a regular termination. In the aforementioned series of processes, the IP telephone terminal is registered in the IP telephony server and is devised to be able to function as a telephone terminal.
Next, there will be described the process in the case where an outgoing telephone call is placed from the IP telephone terminal on the outgoing call side to the IP telephone terminal on the incoming call side. This call connection process is one that is executed between the call connection parts of the IP telephone terminal on the outgoing call side and the IP telephone terminal on the incoming call side, and the call connection part of the IP telephony server.
First, the telephone terminal on the outgoing call side sends an INVITE command, which is a call connection request command, to the IP telephony server. The IP telephony server having received this deduces the IP address, corresponding to the extension number of the telephone terminal on the incoming call side, from the telephone terminal management table and sends an INVITE command destined for the same IP address. Also, the IP telephony server sends a TRYING command, which is a command during processing, to the telephone terminal on the outgoing call side. The telephone terminal on the incoming call side returns a TRYING command with respect to the connection request from the IP telephony server. Next, the telephone terminal on the incoming call side sends, together with sounding a ring back tone, a RINGING command, which is a command during paging, to the IP telephony server. If the IP telephony server receives this, it sends a RINGING command to the telephone terminal on the outgoing call side. If a receiver at the telephone terminal on the incoming call side is picked up, or the like, to reply to the paging, the telephone terminal on the incoming call side sends the “200 OK” command, which is a command to the effect that connection is possible, sent by the telephone terminal on the incoming call side to the IP telephony server. If the IP telephony server receives this, it sends a “200 OK” command, which is a command to the effect that connection is possible, to the telephone terminal on the outgoing call side.
If the telephone terminal on the outgoing call side receives this, it sends an ACK command, which is a connection call completion command, to the IP telephony server and starts the input and output of voice data. The IP telephony server receives this, and sends an ACK command to the telephone terminal on the incoming call side. The telephone terminal on the incoming call side receives this, completes connection control, and starts input and output of the voice data. By means of the aforementioned series of call connection processes, telephone communication is launched between the telephone terminal on the outgoing call side and the telephone terminal on the incoming call side.
In this way, the IP telephone terminal has the characteristic, by registering its own IP address in the IP telephony server after connecting with the IP network, of being able to function as a telephone terminal no matter where it is connected with the IP network. Also, SIP is the standard specification, but there is an extension field in the transmitted and received commands and by utilizing this field, individual data transfers between a telephone terminal and the IP telephony server, or between the telephone terminals themselves, are made possible without modifying the basic call connection sequence.
In free address offices, which have become popular in recent years, what is concerned is an office environment where business operations are possible by connecting one's own Personal Computer (below abbreviated as PC) wherever one is sitting inside the company. In an office environment such as this, best use is made of the characteristics of the aforementioned IP telephony system, so if the IP telephone set having one's own extension number is connected with the IP network at the seat where one has sat down, it becomes possible, by having the IP telephone set carry out registration processing in the IP telephony server, to utilize the set as one's own extension telephone set at the same seat. Regarding the IP address, it is possible for the IP telephone set to acquire it automatically after connection with the IP network by utilizing DHCP (Dynamic Host Configuration Protocol). Also, as an IP telephone terminal oriented toward this free address office, a softphone functioning on a notebook type PC that is comparatively easily portable is appropriate. The utilization of thin clients preventing leakage of information during transport outside the company is spreading and there are also being developed softphones that can also be utilized with a thin client. In an IP telephony system, the effect of being able to “carry along” this number, one's own extension telephone number, is significant, making it possible to place and receive telephone calls with one's own extension number at any base that is connected with the company internal IP network e.g. in the case, during a business trip or the like, of moving to a base office and connecting with the company internal IP network, or the like.
Moreover, since the positions of getting seated are free in this free address office, there is the problem that it becomes impossible to know the seating positions. With respect to this problem, there is proposed, e.g. in JP-A-2005-94127, a method of detecting the seating state used by the telephone terminal. JP-A-2005-94127 is one procedure for detecting the location utilized by the telephone terminal, there being proposed to use the fact that the telephone terminal and the PC are connected as a pair and the PC having a mechanism of alerting the server about the existence of a telephone terminal connected with it. In other words, a PC for transmitting positional information the server becomes necessary, there being the problem that the telephone terminal considered in isolation is unable to detect the same location.